From time to time in the cleaning of catch basins, lagoons, or other facilities, it has become necessary to pump large quantities of extremely viscous material into mobile collection units for transport to appropriate disposal sites.
Heretofore, the sludge transport industry has generally utilized substantially cylindrical trailers which were originally designed to transport industrial grade liquid chemicals, as for example, fuel heating oil, gasoline, etc. Such trucks may either be substantially flat-bottomed trucks or trucks which have one or more low spots disposed thereon which were originally adapted to facilitate the emptying of the liquid materials carried thereby. In order to provide the rigidity necessary in order to reinforce the tanks of such trucks, standard designs have called for interior baffles disposed in planes substantially perpendicular to the longitudinal axis of the tank, which interior baffles are provided at their base with small openings allowing the liquids or other materials contained in those trucks to drain therethrough for emptying.
Unfortunately, unlike almost all industrial grade chemicals, sludges and other industrial wastes are not homogenous, at least as compared with industrial grade liquid chemicals, and often contain large masses of solid materials which tend to clog drainage ports and passages. While it has heretofore been desired to increase the ability of sludge to drain through the drainage ports provided in the interior baffles referred to above by increasing the diameter of those ports, the amount by which the diameter of such drainage ports may be increased is limited by the fact that such ports must be disposed on the lower peripheral edges of such ring-shaped baffles and therefore these ports substantially reduce the strength of the baffles and therefore the value of the reinforcement provided thereby. As a result, free sludge flow during the emptying process is difficult to achieve and as much as from 10 to 20% of the sludge originally carried by the sludge truck remains as residue in the emptied truck and must be maually flushed out to prevent thickening of the sludge to a substantially solid mass upon aging. The manual flushing process is hindered somewhat, however, by the fact that the action of bacteria in degrading the sludge may produce poisonous gases, thereby preventing workers from entering the tank to be cleaned.